Scandal-plagued Toronto Mayor Rob Ford Thursday transferred hospitals via ambulance to a facility specializing in cancer treatment, a day after initial tests uncovered a tumour in his abdomen.

The city's Humber River Hospital announced in a statement that Ford had been moved to Toronto's Mount Sinai "for follow-up investigation and subsequent treatment."

The 45-year-old mayor only returned to work in June after two months in rehab for drug and alcohol abuse, including the use of crack cocaine while in office.

He sought medical help after complaining of abdominal pains that had persisted for more than three months but suddenly became worse from Tuesday to Wednesday.

A CT scan revealed a tumour in his abdomen but the Ford family was still awaiting biopsy results that would determine the type, and whether it is malignant or benign, his doctor Rueben Devlin said.

Ford is seeking re-election in October despite the crack revelations. He is currently running a distant second in public opinion polls behind fellow conservative candidate John Tory.

Prior to seeking help, Ford was filmed numerous times behaving erratically in public, throwing Canadian domestic politics into the global spotlight for all the wrong reasons.

Toronto's city council stripped him of most of his mayoral powers in November over his misconduct.